1. Field of the Invention
The present invention relates to a process for producing an aluminum pipe, and more particularly to a process for producing an aluminum pipe used for a support or substrate of an electrophotographic photosensitive member, which can also be applied to a developing roll of a copying machine, a developer fixing roll and so forth. In particular, it is an aluminum pipe capable of showing a superior performance when used as a substrate for an electrophotographic photosensitive member.
2. Related Background Art
Substrates for electrophotographic photosensitive members have been hitherto produced by a process comprising the steps of working an aluminum pipe or aluminum alloy pipe in a given dimension by hot extrusion or drawing, and thereafter;
A. finishing the pipe to have a surface roughness of 2 .mu.m or less by precision cutting; or
B. finishing the pipe to have a surface roughness of 2 .mu.m or less by rotary pressure rolling (Japanese Patent Application Laid-open No. 3-149180).
Electrophotographic photosensitive members in which an aluminum pipe worked by the precision cutting of the step A is used as a substrate and a photosensitive layer is provided thereon are widely used because of their excellent potential stability. However, the production of aluminum pipes by the precision cutting process requires a long time for their working which does not permit mass-production, resulting in a high cost. Hence, the advent of a substitute process has been sought.
The rotary pressure rolling of the step B is a method by which surface irregularities of the aluminum pipe extruded or drawn are smoothed using rotary pressure rolls. This is a method that can achieve the same excellent surface roughness as that in the precision cutting of the step A. However, the electrophotographic photosensitive member comprising a rotary-pressure-rolled aluminum pipe used as a substrate and a photosensitive layer provided thereon has many problems in its performance and has been unsuitable for its practical use.
In an attempt to produce as an experiment an electrophotographic photosensitive member comprising the rotary-pressure-rolled aluminum pipe used as a substrate and a photosensitive layer provided thereon, a photosensitive layer with a uniform layer thickness has been formed, but nevertheless it has caused so large an unevenness between charge potential and post-exposure potential and also so large a density unevenness in images reproduced that it has been unsuitable for practical use.